Method of producing hydrocyanic acid gas and cyanogen compounds



Patented Dec. 8, 1931 UNITED STATES PATENT OFFICE JESSE P. HUIBIBELL, OF FANWOOD, NEW JERSEY METHOD OF PRODUCING HYDROGYANIC ACID GAS AND CYANOGEN COMPOUNDS No Drawing. Application filed March 23, 1923. Serial No. 627,213.

One general object of the present invendrocyanic acid gas produced in accordance tion is to provide an improved method of with the present invention, the tree is onproducing hydrocyanic acid gas. A second closed in the usual tent employed in fumigeneral object of my invention is to provide gating trees with hydrocyanic acid, and the a novel and commercially economical method calcium cyanide may then be introduced in of producing relatively pure liquid hydrocyto the tent and sprinkled on the ground anic acid, alkaline cyanides, and other relaaround the tree. To effect the conversion of tively valuable cyanogen compounds from the calcium cyanide into hydrocyanic acid relatively crude impure and inexpensive calgas at a reasonably rapid rate, the humidity 10 cium cyanide, by first forming hydrocyanic and/or acid content of the atmosphere must acid gas out of the calcium cyanide, and then be higher than ordinarily obtained at times converting the hydrocyanic acid gas thus when hydrocyanic acid fumigation may be produced, into other valuable cyanogen comsafely and efiiciently carried on. Ihe addipounds desired, by known or suitable methtional humidity may be obtained by wetting 15 ods for producing such compounds from hy the ground either before or after the calcium drocyanic acid gas. cyanide is sprinkled on the ground. In this My novel method of producing hydrocymode of treatment the flaky calcium cyanide anic acid gas consists in exposing a known may be sprinkled on the ground in its inimaterial containing calcium cyanide, to the tial condition, or it may be crushed or pow- 20 action of an atmosphere which will cause a dered before being spread over the ground. relatively rapid conversion of the calcium In lieu of sprinkling the cyanide on the cyanide into hydrocyanic acid gas. The ground, it maybe injected into the tent in crude calcium cyanide containing product powdered form, by means of a dust gun or which I employ as the base material of my the like, and in such case the atmosphere 25 process is known as flaky calcium cyanide, within the tent may be humidified to the deand is a product of the electric furnace which, sired extent by injecting steam into the tent,

as ordinarily marketed, is in the form of relaby spraying a er m s into the tent by tively thin flakes which are grayish black m ns of an atomizer.

in color. It is appreciably less deliquescent T0 accelerate the generation of hydrocythan sodium or potassium cyanide, and its anic acid gas,in fumigatingatree in the manphysical structure as well as its chemical 1161 described, I advantageously add to the composition contributes t it c m r ti l atmosphere, suitable volatile acid constiturapid decomposition into hydrocyanic acid ents. For instance, I may add carbon dioxgas and hydrated lime and/or other calcium ide, a constituent of carbonic acid usually and sodium compounds when exposed to a present in the atmosphere in varying amounts suitable atmosphere, In the cr de comwhich are ordinarily insufiicient to give compound, the calcium cyanide is admixed with pl te, Or as rapid a rate of hydrocyanide gas other materials, the nature and amount of gen a n as is i le- In lie Of, or in which depend somewhat upon the method of addition to augmenting carbonic acid gas manufacture and the relative proportions of constituents of the atmosphere within the the ingredients from which the crude prodfumiga in'g en I may add to the latter atuct is made and in a common commercial omized acetic acid. Other volatile acids may form, the crude product contain about 49 be used, and while hydrochloric, sulphuric percent of calcium cyanide. or nitric acids might be employed to acceler- My invention is well adapted for the proate the generation of hydrocyanic acid gas, duction of hydrocyanic acid gas for di t such inorganic acids are, in general, not ususe as a fumigant to destroy rodents nd able for fumigating purposes, whereas acetic to destroy bugs and parasites which injur acid and carbonic acid in the amounts revegetation. In a preferred mode of treat quired have no tendency to injure vegetation. ing a tree to destroy scale or the like with by In the appended claims the term accelerator is used to include and designate any and all of the substances just mentioned whlch may-be added to the atmosphere in which is used to include and designate an accelera- I to render the tent cloth tor such as carbon dioxide or acetic acid less energetic than hydrochlorite, sulphuric, or

nitric acids which I call strong accelerators.

In treating trees in accordance wlth the present invention, as in other methods of treating them with hydrocyamc acid gas, moisture in the form of dew drops or rain drops on the leaves of trees at the time of treatment isobjectionable since such drops of moisture absorb the gas and the tree may be injured or killed by the gas thus absorbed by the drops of moisture. To avoid injurlng vegetation in this way I consider it ordinar ly' advisable in treating trees in accordance with the present invention to follow the usual practice in fumigating with hydrocyanic acid gas, and treat the trees only when the latter are comparatively dry, and at such times as the humidity of the general atmosphere is ordinarily relatively low. I depart from the usual practice, however, in artificially augmenting the humidity of the atmosphere to the desired degree if necessary. In practicing the present invention I consider the relatively high degree of humidity highly desirable if not essential to the desired rapidity of generation of hydrocyanic acid gas. In general, moreover, I consider it advantageous in fumigating with hydrocyanic acid however it may be generated to operate with a humid atmosphere as I believe this improves the fumigation effect obtainable with a given amount of acid. An incidental advantage of a relatively high humidity in treating vegetation in cloth tents is that themoisture in the atmosphere tends less pervious to gas leakage. In general I consider it desirable that the moisture in the atmosphere should a proach the saturation point but this point should not be reached and generally speaking. a considerable margin of safety is advisable. In ordinary practice I prefer that the moisture content of the atmosphere should be something like percent of that reonired to produce saturation.

The quantit of calcium cyanide required in fumigation in accordance with the present invention. is that which will furnish about the same amount of hydrocyanic acid gas as would be required with the previously known methods of fumigating with hydrocyanic acid gas.

In destroying rodents such as gophers, for

example, I place an ounce or two of calcium cyanide in the burrow or gopher hole, and

acid

then stop up the outlets from the burrow. Advantageously, straw, grass, or the like, is placed over the deposited calcium cyanlde so that the earth used in closing the burrow will not cover the cyanide and interfere with the rapidity of decomposition. Ordinarily the atmosphere in the burrow is suificlently high in carbonic acid and sufficiently humidified by the natural moisture in the earth to make artificial additions unnecessary. In case, however, the burrow is in very dry soil, some water may advantageously be poured into the burrow or on to the earth in immediate proximity thereto, or an acid employed to create the desired condition of the atmosphere in the burrow when the latter is stopped up after calcium cyanide has been placed therein.

In destroying rodents the character of the volatile acid constituents employed to accelerate the generation of hydrocyanic acid gas is in general immaterial except from the standpoint of cost and ease in procuring and handling such constituents.

In lieu of generating hydrocyanic acid gas within the enclosure in which the gas is to be used as a fumigant, I may subject the crude calcium cyanide to the action of a suitable atmosphere in a separate enclosure from which the gas generated is withdrawn for use elsewhere as a fumigant or for other purposes. In particular the hydrocyanic gas thus produced may be used in the commercial quantity production of relatively pure cyanogen compounds, such as liquid hydrocyanic acid and the alkaline cyanides by known or suitable methods for making such compounds from hydrocyanic acid gas. In the production of such compounds, the use of acetic acid as an accelerator has the special advantage that calcium sodium acetate is a resulting by-product of appreciable commer cial value. The present application is in part a continuation of my prior application, Serial No. 520,587, filed December 7, 1921.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. The method of generating hydrocyanic acid gas which comprises the exposure of solid calcium cyanide in an air atmosphere containing some moisture and adding an accelerator to said atmosphere.

2. The method of generating acid gas which comprises the exposure of solid calcium cyanide in an air atmosphere containing some moisture and adding a Weak accelerator to said air.

3. The method of generating hydrocyanic acid gas which comprises the exposure of solid calcium cyanide to the action of atmospheric air and adding moisture and carbon dioxide to the air.

4. The method of hydrocyanic generating hydrocyanic gas which comprises the exposure of solid calcium cyanide to the action of air atmosphere containing some moisture and adding volatilized acetic acid to said atmosphere.

5 5. The method of generating hydrooyanic acid gas which comprises the subjection of solid calcium cyanide to an atmosphere containing some moisture and a volatile acid radical constituent.

I0 6. The method of producing a relatively pure cyanogen compound from calcium cyanide which comprises the exposure of said cyanide in solid form to a gaseous atmosphere containing moisture and an accelerator withdrawing the hydrocyanic acid gas liberated and forming the desired compound from said gas.

7 The method of producing a relatively pure cyanogen compound from calcium cyanide which comprises the exposure of said cyanide in solid form to a gaseous atmosphere containing moisture and a weak accelerator, withdrawing the hydrocyanic acid gas liberated and forming the desired compound from said gas.

8. The method of producing a relatively pure cyanogen compound from calcium cyanide which comprises the exposure of said cyanide in solid form to a gaseous atmosphere containing moisture and carbon dioxide,

withdrawing the hydrocyanic acid gas liberated and forming the desired compound from said gas.

9. The method of producing a relatively as pure cyanogen compound from calcium cyanide which comprises the exposure of said cyanide in solid form to a gaseous atmosphere containing moisture and acetic acid, withdrawing the hydrocyanic acid gas liberated i0 and forming the desired compound from said gas.

Signed at New York city in the county of New York and State of New York this 20th day of March A. D. 1923.

JESSE P. HUBBELL. 

